Hydraulic fracturing, also commonly known as “fracking”, is a technique used in oil and gas recovery from natural, subterranean reservoirs. The technique involves drilling a tubular borehole or wellbore into the ground to a sufficient depth to reach the subterranean oil and gas reservoirs. After reaching a desired depth, the borehole may optionally be drilled along a curve and then continue to run horizontally along a layer of an oil/gas bearing formation.
After a casing is set to secure the walls of the wellbore, a plug apparatus is run into the wellbore, and set at a desired location along the wellbore. A fracking fluid comprising water, a suitable proppant (such as sand grains, metal pellets, or other material) suspended in the water, and various chemicals are injected into the wellbore under high-pressure, and the pressure is applied at the location of the wellbore to create fractures in the surrounding oil/gas bearing formation. The proppant is deposited into the newly created fractures to prop them open, allowing the oil or gas in the formation to be released and collected at a well head.
During a fracking operation, multiple plugs may be set in sequence at multiple locations or zones along the wellbore. After a first zone has been fractured and the surrounding oil or gas extracted, the plug apparatus is drilled out such that another plug can be set in the wellhole, and fracking can occur in another zone.
The performance of the plug apparatus becomes significant to the overall efficiency and performance of the well, as the faster and more effectively a frac plug can be positioned and set, and the faster well can be put on production after use, the more efficient the extraction operation and the better the performance of the oil or gas well. While various frac plug designs have been proposed and designed that can effectively plug a wellbore for a fracking operation, the same frac plug designs may suffer from disadvantages as they may be difficult to mill out after the fracking operation or may have small inside diameters. Lengthy delays may be introduced due to need to mill out or restrict production flow rates using these prior art plugs.
Therefore, what is needed is an improved frac plug design which improves fracking efficiency and performance in comparison to the prior art.